Project Structure and main.ts

shopease-api/
├── src/
│   ├── app.controller.ts        # sample controller (GET /)
│   ├── app.controller.spec.ts   # unit test for it
│   ├── app.module.ts            # root module
│   ├── app.service.ts           # sample service
│   └── main.ts                  # entry point: creates and starts the app
├── test/
│   ├── app.e2e-spec.ts          # end-to-end test
│   └── jest-e2e.json
├── nest-cli.json                # CLI settings
├── package.json
├── tsconfig.json                # experimentalDecorators + emitDecoratorMetadata are ON
└── tsconfig.build.json

src/main.ts

import { NestFactory } from '@nestjs/core';
import { AppModule } from './app.module';

async function bootstrap() {
  const app = await NestFactory.create(AppModule);   // builds the DI container from the root module
  app.setGlobalPrefix('api');                         // every route now starts with /api
  app.enableCors();                                   // allow the Next.js storefront to call us
  await app.listen(process.env.PORT ?? 3000);
}
bootstrap();

src/app.module.ts

import { Module } from '@nestjs/common';
import { AppController } from './app.controller';
import { AppService } from './app.service';

@Module({
  imports: [],                    // other modules this module needs
  controllers: [AppController],   // HTTP entry points
  providers: [AppService],        // services NestJS should create and inject
})
export class AppModule {}